How to use the Hours Calculator

Pick a mode. Between two times: Enter start (9:00) and end (17:30) to get duration. Add / subtract: Enter a start time and an amount to add (8:00) or subtract (-2:30). Sum durations: Paste a list of durations (one per line) — get the total. Convert decimal: Type a decimal (7.5) to get H:M, or a H:M (7:30) to get decimal.

Pourquoi cet outil est important

Timesheets, freelance invoicing, payroll, project tracking, and shift planning all require time arithmetic. Doing it on the back of an envelope produces mistakes. Doing it in Excel requires formula gymnastics (=TEXT(B1-A1,”h:mm”)). An hours calculator is the cleanest answer.

Cas d'utilisation courants

• Freelance invoicing — sum daily billable hours into a weekly total
• Payroll prep — compute total hours from clock-in / clock-out times
• Project tracking — calculate elapsed hours across multiple sessions
• Shift planning — confirm coverage and overtime thresholds
• Estimating project budgets in hours and converting to dollars
• Time-zone planning when scheduling international calls

How decimal hours work

Decimal hours are the standard payroll and invoicing unit because they multiply cleanly with hourly rates. Half an hour is 0.5. Fifteen minutes is 0.25. Forty-five minutes is 0.75. Our calculator handles the conversion in both directions instantly.

Foire aux questions

Does it handle overnight shifts?
Yes — if the end time is earlier than the start time (e.g., 23:00 to 7:00) the calculator assumes the shift crossed midnight and adds 24 hours. The result is 8 hours.

Can I subtract time?
Yes — in “Add or subtract” mode, prefix the adjustment with a minus sign. Type -2:30 to subtract two and a half hours.

What time format should I use?
24-hour format works best (17:30). 12-hour format works if you include AM/PM (5:30 PM). The parser is forgiving.

Can I sum more than ten durations?
Yes — there is no practical limit. Paste hundreds of lines if needed.